Nutrition for Your Long Training Runs


You want your nutrition to rebuild your immune system while maintaining the adaptation in

the muscles that all those miles have produced.

You spend considerable time carefully planning “a long weekend run” when you are training for your next ultra but you may not put the same amount of effort into planning your nutrition during that same run. Since there are no aid stations or crew helping you, how do you carry what you need or practice what you are going to do in the race? As anyone who has had stomach issues in a race knows, practicing sports nutrition is just as important as practicing every other aspect of the ultra run. Figuring out exactly how many calories and the amount of liquids you are going to consume per hour isn’t going to help – or settle well in your system – if you did not train your gut to accept this amount. Plus, the intensity of your effort during a race and the accompanying nervousness only add to the problem.

The Gold Standard
First let’s review what you can actually absorb while running along the trail for hours and hours. The “gold standard” is one gram of carbohydrate per minute. That is four calories per gram or 240 calories per hour for the average runner. If you are male, have lots of lean body mass or are a larger, experienced runner, you may be able to accept more. If, on the other hand, you are female, smaller or new to the sport of ultrarunning, you may only be able to digest about 200 calories per hour. This includes everything you consume – liquids, gels and food. After about four to six hours, you can start consuming protein too, at the rate of one gram protein to three or four grams of carbohydrate. This does not mean you will change the total calorie level, just the percentage that comes from carbohydrate, i.e. from 100% carbohydrate down to 75-80% carbohydrate and the rest from protein. You may be eating some fat in the fuel you consume, but you do not need any for endurance exercise. You have plenty of stored fat in your body, no matter how lean you are, to run for days and days. You may however want to eat some fat for “comfort food”, but those calories are not used during your ultra. It is much more efficient for the body to use ingested carbohydrates (glucose) and the fat already stored than to convert newly ingested fat for energy.

Sweat Rate
Next, you need to know your sweat rate to know how much liquid to consume per hour. Your sweat rate is key to understanding your hydration needs. Average sweat contains about a third of a teaspoon of salt (sodium) per liter or quart (32 ounces). Your blood contains three times as much salt; therefore, as you sweat hour after hour, your blood becomes thicker and more salt concentrated. If you replace what you lose with the same amount of water and salt as is lost in your sweat, your blood will return to normal. If you under-replace the water content, your body will continue to sweat and you will start to become encrusted with salt, lose weight, and become dehydrated. It is not possible to replace all fluids lost, because you simply cannot absorb that much while exercising at a faster than walking pace. If you over-replace the water content, your body will remove water to the surrounding tissues and you will experience swelling in your hands, feet, and under your watchband. You will gain weight and can become hyponatremic. Added to the equation of over-replacing is the fact that kidney function decreases after hours of exercise and you will likely stop urinating, thereby retaining even more water.

Using a scale on a couple of those long practice runs will really pay off when you are actually racing an ultra. Before a training run, go to the bathroom and then weigh yourself in the nude. Run for one to two hours. For ease with the math, drink water or sports drink from a 16-ounce bottle and keep track of how many bottles you consume. When you finish your run, urinate if you need to, towel off, and then weigh yourself again in the nude. If you ran for one hour and consumed one 16-ounce bottle of liquid and weighed the same at the beginning and end of your run, your sweat rate is 16 ounces per hour, half the average. If you lost one pound, then your sweat rate would be 32 ounces per hour, the average. If you gained a half-pound, your rate would be eight ounces per hour. (This would probably only happen to a small runner in winter/cool conditions.) You can then adjust your fluid intake accordingly and start practicing taking in this amount. You may need to do this test both in warm and in cool conditions. Also, as you become an increasingly fit, more experienced ultrarunner, you will become more efficient at staying cooler.

Make a Chart
Now that you have an idea of how much you need to drink (volume) and eat (calories) per hour, put this knowledge to use during your next long training run. Try making a chart similar to the one below, listing all the sports nutrition products, foods, liquids, etc. that you usually consume along with their calories per package or serving and the composition of those calories (carbohydrates, protein, or fat). Once you have this list, you can start to plan the amounts you will need and create a schedule of how often to eat and/or drink. Every 15 to 20 minutes is ideal. If that seems too often compared to what you have been doing, then start with every 30 minutes, but don’t wait longer than that in between feedings. Try using a variety of hydration packs, waist packs, hand-held water bottles, and gel flasks to carry all your fuel and liquids since there will be no aid stations during your practice runs. (Unless, of course, you have an angelic spouse, boy-girl friend, teenager to meet you during your training runs – ha!) Even if the weight is heavier than you might like, it will be a good strength–builder and you’ll feel like flying during the race when you don’t need to carry so much. And rather than trying to remember what you ate and drank all those hours on the trails, just keep the wrappers and when you finish, add up all the calories. This is a great learning experience.

The final part of this project is actually planning a route that can assist you with your nutrition training. A three- or four-leaf clover route is ideal, with your car at the center as an aid station. If this isn’t possible and you are doing an out-and-back course, try parking in the middle and again use your car as an aid station. If you have a chance to get water on your way, you can just carry food and powder mixes to add to your water bottle. If all else fails, you can try to stash supplies along the route beforehand. Set your watch timer to beep every 15 or 20 minutes to remind you to eat and drink. It’s easy to be attentive the first few hours, but then the “ultra haze” sets in and you can’t remember if you ate a gel at the last beep or just drank. A steady supply of calories and liquids will assure that you do not get behind in your fueling and that your stomach will be as trained as your legs.



About Author

Sunny Blende, M.S. is a Sports Nutritionist who writes and counsels individuals and teams on fueling for enhanced performance and making healthy food choices. Currently she writes the nutrition column for UltraRunning magazine and runs ultras herself. She has presented at the National RRCA Convention, the National Rowing Convention, Nike San Francisco Marathon Expo, and the Runners World San Francisco Marathon and worked as an assistant with the Los Angeles Marathon Association. An avid master competitor herself, she trains and competes in the San Francisco Bay Area and beyond. Sunny received her Bachelor of Science degree from University of Southern California and her Masters in Human Nutrition degree from University of New Haven. (Photo at left, by Luis Escobar).


  1. Matthew Schneider on

    Great article I have referred to it on several occasions for the information on sweat rates and salt.

    I have a new question– having run several marathons and other races I am always struggling with GU or gels because after about 3-4 I cannot stand the texture or taste any more and want to get sick. I have tried numerous brands and flavors to no avail. I have eaten bananas, oranges, and other foods but am I really accomplishing what I need to with those foods? Is there a better calorie substitute in terms of whole foods I could try be for when the GU becomes too much or to replace the GU with all together? Is there a blog, page, or article that can help answer those questions?
    Thanks for any advice!